黄土高原沟道小流域土壤水分时间稳定性分析

Time stability analysis of soil moisture in small watershed in the gullies of Loess Plateau

选取黄土高原一典型的沟道小流域坡面为研究对象,利用TRIME-PICO TDR测量了坡面不同坡位下0~1 m的土壤含水率,分析了坡面土壤含水率的变异性和时间稳定性。结果表明,土壤含水率的峰值出现在40~60 cm处,且在不同深度上表现出较大的变异特性,变异系数随深度的增加呈现先增大后减小的趋势,在相对较深的60~100 cm之间的变异性为弱变异,其他深度为中等变异;土壤含水率在不同坡位上表现出上坡位<中坡位<下坡位的趋势,从不同坡位的变异特性来看,不同坡位土壤含水率变异系数表现为上坡位、中坡位变异性较大,呈中等变异,下坡位变异性较小,为弱变异;Spearman秩相关系数法分析土壤含水率的时间稳定性显示,土壤含水率在观测期间不同深度上均具有较强的相似性;不同坡位下土壤含水率在4~6月3个月的观测期间,相关系数均较高,除上坡位的4~5月水分含量不显著外,其他各坡位在时间上的土壤水分含量均显著相关。

A typical channel small watershed slope in the Loess Plateau was selected as the research object. The soil moisture content of 0-1 m under different slopes was measured by TRIME-PICO TDR. The variability of soil moisture content on slope was analyzed. And time stability. The results show that the peak value of soil moisture content appears at 40-60 cm, and it shows large variation characteristics at different depths. The coefficient of variation increases first and then decreases with the increase of depth, and is relatively deep. The variability between 60-100 cm is weak variation, and the other depths are moderate variation;the soil water content shows the trend of uphill position <mid slope position <down slope position on different slope positions, and the variation characteristics from different slope positions It can be seen that the coefficient of variation of soil water content in different slopes shows that the variability of the upper slope and the mid-slope is large, with moderate variation, and the variability of the lower slope is small, which is weak variation. The Spearman rank correlation coefficient method is used to analyze the soil moisture content. The time stability shows that the soil water content has strong similarity at different depths during the observation period;the soil moisture content under different slope positions is higher during the observation period from April to June, and the correlation coefficient is higher. The water content of the uphill position was not significant between April and May, and the soil moisture content of other slopes was significantly correlated with time.